Incidence and Prevalence of Frontotemporal Dementia: A Systematic Review and Meta-Analysis.

Importance: Comprehensive incidence and prevalence rates of frontotemporal dementia are currently not available.

Objective: To estimate the incidence and prevalence of frontotemporal dementia and its clinical variants in the overall population and age subgroups.

Data Sources And Study Selection: We systematically searched PubMed, EMBASE, and Scopus between January 1, 1990, and October 22, 2024, for population-based studies estimating the incidence and/or prevalence of FTD.

Data Extraction And Synthesis: Studies and data were screened and extracted independently by 2 investigators in accordance with PRISMA guidelines. Incident and prevalent cases together with the population at risk were pooled using random-effects meta-analysis. Differences in heterogeneity by FTD variants and populations at risk were estimated.

Main Outcomes And Measures: Prevalent and incident cases as numerator were based on well-defined clinical criteria. Denominators were derived either from census population data or from author-defined populations at risk.

Results: From 1854 screened articles, 32 eligible population-based studies were identified. Sixteen were on prevalence and 22 on incidence reporting FTD measures, including those with estimates for the whole population and for specific age subgroups. Pooled crude incidence for FTD was 2.28 (95% CI, 1.55-3.36) per 100 000 person-years and prevalence, 9.17 (95% CI, 3.59-23.42) per 100 000 people. The behavioral-variant FTD pooled crude incidence was 1.20 (95% CI, 0.67-2.16) per 100 000 person-years and prevalence, 9.74 (95% CI, 2.90-32.73) per 100 000 people. The primary progressive aphasia variant pooled crude incidence was 0.52 (95% CI, 0.35-0.79) per 100 000 person-years and prevalence, 3.67 (95% CI, 3.05-4.43). FTD incidence among individuals younger than 65 years was 1.84 (95% CI, 0.79-4.30) per 100 000 person-years and prevalence, 7.47 (95% CI, 4.13-13.49) per 100 000 people. The denominator based on census data showed less heterogeneity than the population at risk defined by the authors (I2: for incidence, 91.6% vs 97.6%, respectively, and for prevalence, 98.8% vs 99.2%, respectively).

Conclusions And Relevance: In this systematic review and meta-analysis, estimates indicate that FTD is comparable in frequency to dementia with Lewy bodies and occurs at higher rates than progressive supranuclear palsy, corticobasal syndrome, and amyotrophic lateral sclerosis. These results provide a foundation for future research and public health strategy, especially for underrepresented populations, to better comprehend the global burden of FTD. Our findings provide robust pooled estimates of the incidence and prevalence of FTD and its subtypes, offering a foundation for future research and public health planning.